Esters



Patented Oct. 2, 1945 ESTERS Foster Dee Snell and Albert F. Guiteras,New York, N. Y., asslgnors to Chemseareh Corporation, New York, N. Y., acorporation of New York No Drawing. Application February 4,1943,

Serial No. 474,718

18 Claims. l'Cl. 106-8) This invention relates to new organic compoundsand particularly to esters of higher aliphatic alcohols and higher fattyacids having properties similar to those of certain natural waxes.

It has been understood heretofore that the natural waxes contain a largeproportion of esters of unsubstituted'higher aliphatic alcohols andunsubstituted higher fatty acids. Attempts to synthesize wax substitutesby esterification of unsubstituted higher aliphatic alcohols andunsubstituted higher fatty acids' have been made heretofore. Suchprocedure necessarily requires alcohols and acids of very largemolecular weight which are obtainable only with considerable difficultyand at great expense. Hence it has not been practicable to produce waxsubstitutes for commercial use by the procedure indicated.

It is the object of the invention to afford new esters which may beutilized for various industrial purposes and which are especiallyvaluable as substitutes for natural waxes and as ingredients of waxcompositions employed for polishing and other purposes.

Other objects and advantages of the invention will be apparent as it isbetter understood by reference to the following specification, in whichthe examples are set forth without limiting the invention to theparticular procedure and constituents described.

We have discovered that valuable esters having commercially desirablecharacteristics can be prepared by esteriflcation of straight-chainsaturated alcohols and straightehain monocarboxylic fatty acids in whicheither the alcohol or the acid has a hydrogen replaced by one and notmore than one hydroxy group, both the alcohol and the acid representedin the ester containing substantially not less than 16 nor more than 24carbon atoms. Such esters are monohydroxy esters of the alcohols andacids as defined.

These esters have relatively high melting points, are hard at ordinarytemperatures, susceptible of application to give a high polish andtherefore suitable for use as a polishing wax as well as for otherpurposes where the esters can replace waxes of natural origin. Numerouspossible uses of the esters other than as polishing materials willoccur.

It was to have been expected that monohydroxy esters of the kinddescribed would have properties approximating those of correspondingnon-hydroxy and dihydroxy esters. It has been found, however, that themonohydroxy esters have quite different characteristics. Thus, the

new ester, octadecyl monohydroxystearate, prepared according to theinvention, is hard at ordinary atmospheric temperatures. When used as apolishing wax, it gives a good gloss, and it can be used in substantialamounts in commercial self-polishing wax compositions.

Octadecyl dihydroxystearate on the other hand has a soft and greasyfeel. Likewise, octadecyl stearate containing no hydroxy group is softto the touch. Neither is suitable for use as a substitute for theproducts of the present invention. Both octadecyl stearate and octadecyldihydroxystearate when made into a gel of 50% concentration with mineraloil show bleeding out of the solvent on standing, whereas the gel withthe new ester octadecyl monohydroxystearate shows no bleeding undersimilar conditions. Compatibility with mineral oil is essential to a waxwhich is to ed, containing approximately 16 to 24 carbon atoms to themolecule. Examples of acids which are suitable are the monohydroxyderivatives of palmitic, stearic, arachidic and behenic acids. Morespecifically we may use to advantage alphahydroxy palmitic acid,CH3(CH2)13CHOHCOOH, alpha-hydroxy stearic acid CH3 (CH2) 15CHOHCOOHalpha-hydroxy arachidic acid ormcm) ncnorrcoon and 12-hydroxy stearicacid CH3 (CH2) 5CHOH(CH2) ioCOOH the latter being particularly suitablein forming esters with 016-024 alcohols which are excellent waxes. Theacids referred to may be considered as hydroxy-soap-forming acids.

As the alcohol to be esterifled with such acids,

we select one which is a straight chain saturated and preferably primaryalcohol containing not substantially less than 16 nor more than 24carbon atoms to the molecule, as for example hexadecyl, CH3(CH2)14CH2OH,heptadecyl CH3 (CH2) 15CH2OH and octadecyl CH3(CH2)16CH2OH alcohols. Itappears that the orientation of the structure is interfered with bybranching of the chain. Thus, a product of a branch chain acid orsecondary alcohol is inferior to that 'of a straight chain acid orprimary alcohol.

When the hydroxy group of the finished ester is to be supplied by thealcohol, the acid selected should be an unsubstituted fatty acidcontaining about 16 to 24 carbon atoms, as for example palmitic,cI-mcrn) 14COOH, oleic or stearic acid crmcmmcoon. The acid isesterifled with a diol containing approximately 16 to 24 carbon atoms,preferably having the -OH groups on the end carbons of a straight chainmolecule. Examples of diols which may be used are 1,12-octadecane diolCH1(CH:) sCHOH(CI-I2) mCHrOH 1,16-hexadecane diol, CHzOH( CHr)14CH2OH.and 1,18-octadecane diol, cmomcmmcrnon.

We prefer to use a hydroxy soap-forming acid and a non-substitutedalcohol such as octadecanol CH3(CI-I2)1sCI-I2OH rather than anunsubstituted acid and a diol. If diols are used, isomers may be formed,and unless the hydroxyls are on the terminal carbons, branching resultsin some of the molecules. The product may be used for many purposes,although not quite so satisfactory as one produced by esterification ofmonohyclroxyacid with a non-substituted alco- Whether the substitutedhydroxy group is initially present in the acid or in the alcohol, theesterification is eil'ected by combining the selected acids and alcoholswith the aid of a suitable catalyst in the proportions of substantiallymol for mol. The preferred catalyst is p-toluene sulfonic acid, butother catalysts may be employed, as for example sulphuric orhydrochloric acid. The latter catalysts are not quite so satisfactory asthe p-toluene sulfonic acid.

In preparing the ester, the selected higher alcohol and the higher fattyacid are mixed in a melted condition. The esterification is effectedunder conditions that promote reaction and preferably also remove, byvolatilization, water formed in the reaction. Suitably the mixture ofalcohol and acid in approximately equi-molecular proportions is mixedwith a small proportion, say 0.05% to 1%, of the esteriflcationcatalyst. The mixture is heated so that esterification proceedsrelatively rapidly and preferably to a temperature somewhat above theboiling point of water, the water formed as a byproduct ofesterification being removed from the sphere of the reaction byvolatilization.

Removal of water may be facilitated by vacuum or passage of an inert gasthrough the mixture. Nitrogen may be used as the inert gas and improvesthe color by reducing air exposure. It also reduces the final acidvalue. The temperature should at all times be kept below that at whichprogressive darkening or decomposition of the alcohol, acid andresulting ester occur to an objectionable extent.

When tests show that the acid is substantially completely esterifled,the heating is discontinued and the product is suitably cooled to atempera-' ture slightly above the melting point. The product may then betreated in any'conventional manner for removing the acid catalyst fromthe water insoluble ester. It may, for'example, be washed with severalportions of water to remove the acid catalyst, or there may be added andstirred into the molten mass a small proportion assasco of aneutralizing agent for the catalyst as for example finely dividedcalcium carbonate, anhydrous sodium or potassium acetate. or ammonia.strictly necessary in many cases. v

The invention will be further illustrated by the following specificexamples:

As a typical case, 12-hydroxy stearic acid is first obtained fromanysuitable source. It may be made by hydrogenating castor oil,saponifying the hydrogenated product, acidifying the soap so produced,and then separating the fatty acid from water soluble substancespresent, all in a conventional manner. The fatty acid so made consistslargely of 12-hydroxy stearlc acid and is sufficiently pure for thepurpose of the invention.

The 12-hydroxy stearic acid prepared as described or in any other manneris melted in a steam-jacketed kettle with octadecyl alcohol. The alcoholand acid are used in approximately equal weights, as for example, 144parts by weight of monohydroxy stearic acid to 130 parts of octadecylalcohol. The catalyst consisting of one part by weight of p-toluenesulfonic acid of the 74%-75% commercial grade is added. The whole isstirred with a slow mechanical agitator and maintained at a temperatureof about nil- C. for approximately 2 to 4 hours.

Tests made during the heating of the batch show that the acid valuedrops to about 4.8 and the melting point of the product rises graduallyand then becomes practically constant. The catalyst may be removed bywashing or it may be neutralized. The product is then allowed to coolpartly and is cast in suitable receivers such as metal molds. There isthus obtained a yield of 241 parts, consisting largely of octadecyl 12-hydroxy stearate CH3(CH2) sCHOH(CHa) 1oC'OOCH2iCI-I2) CH:

having a melting point of approximately 71 C. When re-crystallized fromwarm alcohol, we obtain purified octadecyl monohydroxystearate meltingat approximately 73 C.

Other esters are made by substituting other alcohols and other fattyacids of the class described mol for mol for the octadecyl alcohol andmonohydroxy stearic acid respectively in .the above example. Providedthe alcohols and acids are selected as described, the esters haveproperties similar to the ester obtained in accordance with the example.7

Following the same procedure as in the preceding example, we can produceesters of non-hydroxy monocarboxylic fatty acids with diols. Thus theester of stearic acid with 1,12 -octadecane diol is obtained byesterifying these compounds under the conditions described. This esteris 12-hydroxy octadecyl stearate CH3 (CH2) 1sCOOCHa(CI-I2) 10CHOH(CH2)sCH:

Other non-hydroxy acids of the same class may be combined with otherdiols to produce commercially valuable esters. The esters havecharacteristics similar to those resultin from the practice of theprocedure in which hydroxy acids are combined with monohydric alcohols.The polishing characteristics are not quite so good, but the esters aresuitable for many purposes.

When the alkyl monohydroxy acid ester is to be used in a polishdispersed in water, the ester is preferably blended with carnauba wax orother natural materials and those minor ingredients 'which areconventional in water dispersible wax polishes. The proportions ofcarnauba wax Removal of the acid catalyst is not assasca intention tolimit the invention to such specific examples.

We claim:

1. A monohydroxy ester of a straight chain saturated monocarboxylicfatty acid and a straight chain saturated alkyl monohydroxy alcohol,each containing not less than 16 nor more than 24 carbon atoms to themolecule.

2. A monohydroxy ester of a straight chain saturated monocarboxylicfatty acid and a straight chain saturated alkyl alcohol, each containingnot less than 16 nor more than 24 carbon atoms to the molecule, in whichthe hydroxy group occurs in the acid portion of the ester.

3. A monohydroxy ester of a straight chain saturated monocarboxylicfatty acid and a straight chain saturated alkyl alcohol, each containingnot less than 16.nor more than 24 carbon atoms to the molecule, in whichthe hydroxy group occurs in the alcohol portion of the ester.

4. A monohydroxy ester of l2-hydroxystearic acid with a straight chainsaturated allwl alcohol containing approximately 16 to 24 carbon atomsto the molecule.

5.-A monohydroxy monoester of octadecane diol with a straight chainsaturated fatty acid containing approximately 16 to 24 carbon atoms tothe molecule.

6. Octadecyl 12-hydroxystearate CH3(CH2) sCHOH(CH2) 10COOCH2(CH2) 1sCHa7. l2-hydroxyoctadecyl stearate CH3 (CH2)1sCOOCHz(CH:)1oCI-IOH(CH2)sCI-Ia 8. A polishing composition comprisingan intimate blend of the synthetic wax described in claim 1 and carnaubawax, the carnauba wax increasing the dispersibility of the synthetic waxin water.

9. A polishing composition comprising an intimate blend of the syntheticwax described in claim 1 and a natural wax, the natural wax increasingthe dispersibility oi the synthetic wax in water.

10. A saturated monohydroxy monoester con-- sisting of the reactionproduct of equimolecular amounts of a saturated straight chainmonocarboxylic fatty acid and a saturated straight chain alkyl alcohol,each containing not less than 16 nor more than 24 carbon atoms to themolecule.

11. The method of producing monohydroxy esters in which the hydroxygroup occurs in the acid portion of the ester which comprises reacting astraight chain saturated monohydroxy ters in which the hydroxy groupoccurs in the acid portion of the ester which comprises reacting astraight chain saturated monohydroxy monocarboxylic acid containing notless than 16 nor more than 24 carbon atoms to the molecule with asubstantially equimolecular amount of a straight chain saturated alkylmonohydroxy alcohol containing not less than 16 nor more than 24 carbonatoms, and maintaining the mixture at a temperature above the boilingpoint of water at the existing pressure during esteriilcation, so thatwater formed as a by-product of the esteriilcation is removed.

13. The method or producing monohydroxy esters in which the hydroxygroup occurs in the acid portion of the ester which comprises reacting astraight chain saturated monohydroxy monocarboxylic acid containing notless than 16 nor more than 24' carbon atoms to the molecule with astraight chain saturated alkyl monohydroxy alcohol containing not lessthan 16 nor more than 24 carbon atoms, andmaintaining the mixture, inthe presence of an esteriflcation catalyst, at a temperature above theboiling point of water at the existing pressure during esteriilcation,so that water formed as a by-product of the esteriflcation is removed.

14. The method of producing monohydroxy esters in which the hydroxygroup occurs in the acid portion of the ester which comprises reacting astraight chain saturated monohydroxy monocarboxylic acid containing notless than 16 nor more than 24 carbon atoms to the molecule with astraight chain saturated alkyl monohydroxy alcohol containing not lessthan 16 nor more than 24 carbon atoms, maintaining the mixture at anelevated temperature until esterification has taken place, and removingwater formed as a by-product of the reaction by blowing through theresulting ester 9. gas inert thereto.

15. The method of producing monohydroxy esters in which the hydroxygroup occurs in the acid portion of the ester which comprises reacting astraight chain saturated monohydroxy monocarboxylic acid containing notless than 16 nor more than 24 carbon atoms to the molecule with astraight chain saturated alkyl monohydroxy alcohol containing not lessthan 16 nor more than 24 carbon atoms, in the presence of anesteriflcation catalyst, and removing water formed as a by-product ofthe reaction by blowing through the resulting ester 2. gas inertthereto.

16. The method of producing monohydroxy esters in which the hydroxygroup occurs in the acid portion of the ester which comprises reacting astraight chain saturated monohydroxy monocarboxylic acid containing notless than 16 nor more than 24 carbon atoms to the molecule with asubstantially equimolecular amount of a straight chain saturated alkylmonohydroxy alcohol containing not less than 16 nor more than 24 carbonatoms, in the presence 01' an esteriflcation catalyst, and removingwateriormed as a by-product of the reaction by blowing through theresulting ester a gas inert thereto.

17. The method of producing monohydroxy esters in which the hydroxygroup occurs in the alcohol portion of the ester which comprisesreacting a non-substituted straight chain saturated monocarboxylic acidcontaining not less than 16 nor more than 24 carbon atoms to themolecule with a saturated straight chain alkyl diol containing not lessthan 16 nor more than 24 carbon atoms to the molecule, and removingwater formed as a by-product during the esterification by blowingthroughthe ester a gas which is inert thereto.

18. The method of producing monohydroxy esters in which the hydroxygroup occurs in the alcohol portion of the ester which comprisesreacting a non-substituted straight chain saturated monocarboxylic acidcontaining not less than 16 nor more than 24 carbon atoms to themolecule m water at the existing pressure during esterification, so thatwater formed as a by-product of the esterification is removed.

FOSTER DEE SNELL. ALBERT F. GUITERAS.

